ELECTRONIC EXCITED-STATES OF NO CU(111) STUDIED BY HIGH-RESOLUTION 2-PHOTON PHOTOELECTRON-SPECTROSCOPY/

A high-resolution two-photon photoelectron (2PPE) spectrometer was con structed and applied to NO adsorbed Cu(111). The apparatus was based o n a high-repetitive tunable laser of picosecond pulse duration combine d with a single-electron counting time-of-flight (TOF) system. Perform ance of the apparatus was examined with 2PPE spectra of Ag(111) and Cu (111) surfaces, Energy resolution better than 0.03 eV was achieved. A preliminary result for NO adsorbed Cu(111) surface showed that electro nic states of adsorbed NO contain some fine structures, suggesting tha t the high-resolution 2PPE spectroscopy provides much information on e lectronic structure of adsorbed molecules.